If this is your first visit, be sure to
check out the FAQ by clicking the
link above. You may have to register
before you can post: click the register link above to proceed. To start viewing messages,
select the forum that you want to visit from the selection below.

Re: Designing good daytime rear commuter lights

Originally Posted by Savvas

I've actually just discovered the Nichia Regal led which seems to be available in red from LEDSupply (though they seem to have some problem posting to Australia), Anyway, it seems to have a v/low Vf of 2.? volts. Three would seem to be a great combination for a rear dynamo 'running' tail light.

2.x volts are common for reds, and if you're happy with commercially available dynamo front lights, a triple rear is possible, running in parallel to the front.
If building the front light yourself, you might hook up the rear in parallel to two or three front LEDs, thus only needing one rectifier in the front light. Simply add a resistor to adjust the current for the tail.

But this is about powerful rear lights, so you'll likely want a 3 watt red in series to the front, maybe two. It all depends upon what distribution of front and rear light power you'd like.

For Germany, a single 5-mm-LED running at 50mA is plenty when combined with an optic glued into a red plastic retroreflector.
The transparent glue allows some light to pass into the surrounding plastic, giving a good combination of punch and side visibility.
For daytime use, I just about finished a dual-5-mm setup in a larger retroreflector, combined with these oval optics. Again running at 50 mA, so there is not a lot of loss to the front (I'm running these from a dynamo as well, so somewhat limited power supply).

Re: Designing good daytime rear commuter lights

Originally Posted by Savvas

.... I think that circuit (#10?) has the doubler built in doesn't it? ...Sam.

Circuit 12 I think. No matter. I think he only offered the doubler one as a board. Also those were 6 Luxeons. and likely 3.4 Vf at 500 mA or thereabouts. Wired up for three LEDs, the XP-G's don't offer enough Vf so my tuning pot is at no resistance, I could afford some more VF like two Red LEDs in parallel or a 2s2p quartet.

Re: Designing good daytime rear commuter lights

Re: Post 150 & 151
Photos please.
Sam - I reckon if you use the Al sheet as the exterior back of your new light that you won't have much of a problem with heat. I'm always impressed with how little heatsink you need when you have air movement.
If you're still concerned you can always bond a commercial heatsink to it.
What driver have you decided to use?

Re: Designing good daytime rear commuter lights

"Sam - I reckon if you use the Al sheet as the exterior back of your new light that you won't have much of a problem with heat."

Yep - that's what I had in mind. I bought the 55mm tube (51mm I.D) with the idea that both the 'tube' and the triple lense will bond independently to an alu macking plate with a bit of silicon sealing an slight gap between them.

"What driver have you decided to use?"

I have a couple of Taskled CC5Ws - basically 'on-off' with a once-only setup choice of currents. Not sure which current setting to use though - advice most welcome! I also have a few DX drivers which I think are boost - they came as a set of 4 but I can't recall which ones they are. I may try them as I really don't want to use a large battery.

Actually I think your 50mm design is also going to be a 'test bed' for my dynamo experiments. I have been using square-section castoff plastic chip tube from the waste recovery centre (which makes building on a bit of veroboard easy) but the idea of using optics as well as clear housing makes a lot of sense.

I agree that it's full-on brightness we're after for running lights, especially for commuting, but I would really like to satisfy my curiosity regarding dynamo power! I am quite happy with the edelux up front so I guess I'd like to focus on a complementary rear light. I have a bag of red and white 100ma Superflux leds from ebay which I reckon would benefit from housing behind a cheap DX MR16 triple optic. I could run 3 behind the optics and a couple more facing sideways - all arranged in parallel - and still maybe have enough dynamo current to drive a series triple at the front.

Re: Designing good daytime rear commuter lights

Originally Posted by 1 what

Re: Post 150 & 151
Photos please.

Real life conditions not available atm, so regulated 6V/50mA in direct sunlight.
Not as much magenta as my cam makes out of it, but still not the perfect red. These are salvaged 5mm-LEDs, not as bright as the ones from the above link.
Once I have my video cam I'll try to show how this holds up against traffic.

Re: Designing good daytime rear commuter lights

Hi Sam.
If I understand you correctly that quote referred to the "3 in 1" light that I photographed in post # 29.
It's now off the bike replaced by the 2 LED light in post#138.
I'll reconnect the 3 in 1 over the next 2 or 3 days and post some photos.
Thanks for your interest.

Re: Designing good daytime rear commuter lights

Thanks 1 What,

Yes - the light I was referring to was the all-plastic, cylindrical, 3-led one in post #29. I'm interested in its construction and optical results more than anything. Hence the request for a night time pic. Please don't go out of your way to reconnect it - only if convenient.

There seems to be some amazing synergistic thinking on this list. Your post #138 more or less mirrors a light I've been working on except I'm using Ledil flare optics rather than the round diffuser you have and a horizontal alloy channel construction. Not finished yet but I really like your diffuser lens - suspect it may be more effective than the flare, but we'll see.

I've realised that my lighting needs (for commuting) are mostly in the middle ground rather than the extremes. Like many riders I have a lot of blinkies that get various levels of use. One of the best I have is an old Vetta TLS-2 (?) that's about 50mm across and has (I think) 16 5mm LEDs. Optically and electronically it's nothing special EXCEPT its very, very eyecatching and visible. I'm not sure why but I think it's the overall size of the light and the fact that it's light is 'attention getting' but 'non-dazzling' - if that makes sense. I want to explore this whole 'conspicuity' thing as I'm sure that brightness is not all there is to it...

Re: Designing good daytime rear commuter lights

Re: Designing good daytime rear commuter lights

Photo as promised.
Both visually and as far as the camera was concerned the smaller diameter brighter light out classed the larger diameter light.
But...Both looked very bright and the larger diameter 3 in 1 light only uses about 1/4 of the power of the smaller brighter light. So if battery run time is an issue....

Re: Designing good daytime rear commuter lights

Thanks 1 What,

Don't know how you created that image but it's very effective - I'm very impressed with both lights! Especially the side view of the triple. But the 2 led tail light is so bright! I'll go back and look at post 138 again in detail.
Thanks again!

Re: Designing good daytime rear commuter lights

Good Job 1 What. I use Power Point to set background, load images and crop them, add text arrows, and save as a jpg file to load to service. But I know that program cold.

This takes some time. What it does though, is force a discipline and thought about what you see/saw. So in effect, you learn more because you are forced to, so I find it very worthwhile for me. Hope you did, too.

Size & power & distinctiveness matter more if you are one light in many. Power matters more if you need to punch through cell phone drivers attention in the day. It is also of great use, though at reduced levels, for night use on the shoulder of fast highways, where you want a long distance warning, or instant warning as they come out of corners or over hills to see you for the first time. Wide angle matters more if riding past a lot of cross traffic day or night. One simple blinky isn't up to all these tasks.

I came upon a cyclist in white Jersey about 2 hours before civil dusk on Tueday night. Though in a more crouched position than I usually use, with less back visible, he was readily seen though not what I would call conspicuous, with no lights whatsoever. So I really think this is about getting through to inattentive drivers, and there are far too many of them being far too unsafe and not thinking about passing a cyclist until they re on top of him/her. I want "I did not see him" to be self inciminating, not a shift of the real blame.

Look at the effort we are applying to go beyond what is required by law!

I might get some night & day video in. My main light mule hass had some frame mods and is being shipped back, so I'll have to use the errand bike. have to know where I'm now before changes.

Re: Designing good daytime rear commuter lights

Select red. Multiple output levels. No flash though. A flashing circuit ahead of it should work, though. 10 W for 3 XP-G which are 3.3 Vf at 1 A says ! A max current, too hot for the reds. The 5 W aould be about 0.5 A. Presumably the voltage setting resistor would be changed so that 700, 350, 175, and 70 mA or so would be the settings. If so, the N3 bin Reds would be about 240 lumens out the back with the wide optic at max level.

They have a narrow optic, but that is not really what is needed in a tail light of this power.

The frosted wide loses 20% of the output but you get 37 degree FWHM coverage.
Could be wider but if the side output was let loose as in 1 What's triple, it might do.

Both total, a little under $33 US at current exchange rates.

About 5 watts total so a 7.5 sq. inch surface area housing or a bit more would do. A 2" long 1" OD aluminum tuve with 1/8" walls, 1/16 minimum. Might squeeze into one of the $2 9 LED flashlight bodies.

Re: Designing good daytime rear commuter lights

I ordered a couple. I have a need for lights that stay solid. Flashing would be nice, but I don't think flashing is going to be an option, and the high setting might just be a full loss. Maybe I'm wrong, we'll see. I'm not really in a position to pay for a software change to add flashing, and I suspect that whining wouldn't get it done either. I think it was conceived as a front light. They don't heavily promote it, which is too bad.

It looks like the straight back blinkies either the Radbot 1000 or the Planet Bike Turbo can be seen in this light from a considerable distance, but the wider angle 100 lumen DIY could use more power.

When the driver is closer and the road is straight across, the 45 degree angled headlight hangs in to just before crossing in front, and that is without the driver turning to look at the bike. To me this suggest maybe even side firing at handlebar height might be good, though helmet height might be seen over shorter vehicles and obstructions like mailboxes. The 45 degree tail light shows up later but a driver sould have been moving forward so they would be seen closer but not soon enough.

Re: Designing good daytime rear commuter lights

I suggested a red or red-orange version when he reported the first triple module. Nice to know they exist. Suspect a misprint Red. Won't be "R2' bin. Reds go to N3, Red-oranges to P3. Suspect Red-orange P3. which is as good as they get.

I bought one of these MR-16 lights from DX and started fiddling about with it. Noted that you said that it is 'polarity neutral' so I assume it has a bridge rectifier inside. Is this the case?

Connected it to a Micropuck (5v out) and got what I assumed is the 'reduced output' mentioned in the DX blurb. Swapped polarity and it still worked OK so maybe I've answered my own question...

Incidentally I also put this across the terminals of my SON dynamo and gave it a spin. Very bright although also very directional and with quite a bit of flicker (probably a good thing). Bought some ping-pong balls so may cut one up as a diffuser experiment.

Re: Designing good daytime rear commuter lights

I bought one of these MR-16 lights from DX and started fiddling about with it. Noted that you said that it is 'polarity neutral' so I assume it has a bridge rectifier inside. Is this the case?.

Yes, in the white plastic rectrangular part between the pins and the curve. If running DC opnly a bit extra efficientcy can be gained by bypassing the diode bridge.

QUOTE=Savvas;3673009]Connected it to a Micropuck (5v out) and got what I assumed is the 'reduced output' mentioned in the DX blurb. Swapped polarity and it still worked OK so maybe I've answered by question...

Incidentally I also put this across the terminals of my SON dynamo and gave it a spin. Very bright although also very directional and with quite a bit of flicker (probably a good thing). Bought some ping-pong balls so may cut one up as a diffuser experiment.

Sam.[/QUOTE]

I am surprised you got something. Mine spec'd 9 vt min and 16 volt max. The lowest I put through them is 9 volt.

Flickering is expected with no smoothing cap. Yes, at first I liked the directionality as I was having drivers come within 10 feet and still a bit fast when they could not pull out due to oncoming traffic. THAT behavior is very unnerving when you can't keep an eye glued to your mirror. The ANSI vest seems to get them aware I am there sooner so they plan better. So the narrow beam is not as necessary as at first.

I have one of those horizontal flare lenses I bought from Cutter's on a whim since it was cheap and I was paying postage anyway. I thought might work but explored the bubble lens first. I think it plus the bubble might be what I need. I could reduce power simpy by supplying less, if you are getting light with 5 vt. I have these 8.4 small cells from the now antiquated Sony and they will die anyway so why not use them?
They could be used in series for high, parrallel for low.

In the thread on your dyno lights, you made a point that has been niggling me in the back of my mind wrt side view. The splayed out headlights do a great jub until just before you cross in front of approaching cross traffic.

The rear does not show well for another 20-40 feet using the narrow beams of the MR16 modules. I would guess a turn from a side street into the rear of a bike that has passed by, but not been seen by a cross street driver, is pretty rare. With 100 lumen + splayed out lights, it would require someone pretty impaired not to see the bike.

At night, the lights show pretty well from the side whether front or back, though the rears would be less bright to a following driver if splayed out and more side lighting would be better. It seems to me that it is your sudden appearance unheraladed broadside in front of the car that is the issue. The bright front lights have stopped 'too-close' left turns in front of me from either cars on my left or approaching cars day and night.

So it is the coming into a broadside on zone that needs help. A wide angle horizontal and narrow top to bottom beam from no lower than the fork crown to handlebar height (even the helmet though that gets heavy unless batteries are shared), aimed to each side, run on high power in the day, and low at night to save cyclists night vision, and because you simply don't need to be as bright as a car headlight to the side at night, might do the trick. White would work with an amber lens, likely more lumens per watt even after lens losses than using a true amber LED which are very temperature sensitive. A tube with an LED and flare lens on each end, driver and a pair of Li-ion cells, with switches and charge port might do the trick. The rescued light leaking sideways off optics like 1 What's triple tail light works well at night as does my helmet light's amber hood. There just isn't enough side output in the day. Turning my head and aiming the helmet light works very well, it requires me to see them coming and if there is a driver to either side, it isn't adequate. So I think I have another light to make. A double ended front clearance lamp.

Re: Designing good daytime rear commuter lights

Interesting...It seems we're all working away on the same thing
Mine is being delayed waiting for parts so you chaps will probably post ahead of me.
What I'm really looking forward to is seeing how similar (or dissimilar) our lights are.

Re: Designing good daytime rear commuter lights

This is my third attempt to post this message.... will it work this time?
EXCELLENT!

I’ve been thinking about the issues in building better rear lights and the progress made thus far. It seems to me that we are in danger of developing “bloated” “electron guzzling” designs with higher and higher output. A bit like the muscle cars of the 80’s – very powerful and great fun but not very efficient (especially if we have to carry our power around in batteries). In saying this I admit that I’m as guilty as anyone else – using more and more powerful LEDS.Can we discipline those valuable photons and make a more efficient light?So I was off on an early morning ride recently and started thinking about the Star Ship Enterprise…then the Hadron Collider (please don’t ask me why….maybe my brain was cold since it was 5 degrees). Then I realized that maybe we’ve been trying to build lights of the wrong shape especially if we want better side and front visibility (not to mention a different type of output for daytime use).So why not do this:

For daytime use the light tube could be open and for night time use we could clip a diffuser over it (Fenix make one that latches open and shut and fits a 22mm tube)…..So if the light tube is a 22mm acrylic tube it will fit the Fenix diffuser.This is how it looks in real life:
The light pipe has been extended and the CREE XPE red LED is inside an 18mm DX reflector.
I've added a couple of rare earth magnets to latch the diffuser open or shut (ie daytime and nighttime mode).
Here's how it looks on the bike:

And heres how it looks at night:

I've included the 3 in 1 light from post 137, 138 for comparison. It's plenty bright enough for nighttime use and easily seen in daylight.....But here it is in daytime mode ( diffuser latched open):

Yes a CREE XPE at 750mA puts out a few lumen. Excellent day time visibility - same as the day time light in post 138.

It presents a side profile of 70mmx30mm at full brightness:

And if you move around to 135 degrees from the back it is still very visible:

So... the concept continues to develop and this model is much more robust and waterproof than the one in post 138..

Re: Designing good daytime rear commuter lights

1 what,
Very, very impressed! Could you please talk us through exactly how this works as it's not entirely obvious to me I'm afraid. I'm curious how the reflecting base and the light pipe and adjustable diffuser work.

I find your intro re 'muscle cars' etc interesting and quite relevant! If we trace the history of innovation from the pre-industrial age into and through the phases of the current technological age we can see many examples of the evolving forms of specific tools or other functional items in which, while materials have developed, the actual form has often not, remaining constrained conceptually by basic concepts left over from the first iteration as the item was first conceived.

For example, the first cars were built like, looked like and drove like horse drawn carts for a couple of decades until metal fabrication caught up with the manufacturing of the IC engine.

Most bike head lights depend on some form of hemispherical reflector or some form of circular refractor lense, or in the case of tail lights, some form of coloured refractor and diffuser, much as lights have done for over 100 years. Very few really try to utilise the light transmission and/or diffusion benefits of modern plastics. Indeed it could be argued that the reflector and refraction mechanisms of most bike lights are hold-overs from a time when the light was required to concentrate as much as possible the relatively feeble output of a 3 watt (or lower in the case of taillights) filament bulb! About the only example I know of that does seem to play with the 'new optics' is the new B&M Topline tail light (and the NightLightning AftaBlaasta and the NightFlux Red Zone of course).

1 what's design IMHO is a bit of a breakthrough, especially given the simple materials involved. It sheds the obsession with reflectors/refractors as the light's main 'mechanism' and acknowledges that lighting design based on transmission and diffusion could perhaps better serve the tremendous output of modern LEDs - at least for a 'be seen' light anyway!

This seems an excellent example of innovative thinking! If only I could understand it...

Re: Designing good daytime rear commuter lights

Thanks Guys.
A very quick response since I'm in the process of leaving for a five day trip....Will be back late Sunday night and straight into a very busy week. To date I've not even had a chance to take it for a ride since I wanted to post it as soon as I could.
I'll take some better photos (incl daytime for Brian) and go into details as soon as I can next week. Have a good weekend.